Related Experiment Video
Updated: Jun 24, 2026
10:25
Single-Digit Nanometer Electron-Beam Lithography with an Aberration-Corrected Scanning Transmission Electron Microscope
Published on: September 14, 2018
Optimum beam transfer in the environmental scanning electron microscope
1ESEM Research Laboratory, 28 Wallis Parade, North Bondi (Sydney), New South Wales 2026, Australia. gerry@danilatos.com
Journal of Microscopy
|April 2, 2009
Summary
This study models gas density in environmental scanning electron microscopes using the direct simulation Monte Carlo method. It optimizes electron beam transmission, crucial for high-performance instruments.
Area of Science:
- Physics
- Materials Science
- Engineering
Background:
- Environmental scanning electron microscopy (ESEM) requires precise control of gas environments.
- Pressure-limiting apertures are critical for maintaining differential pumping in ESEM.
- Understanding gas dynamics and electron beam behavior within these apertures is essential for instrument performance.
Purpose of the Study:
- To determine the gas density of argon along the axis of a pressure-limiting aperture in an ESEM.
- To investigate electron beam transmission through the aperture for various gases and conditions.
- To provide a basis for designing ESEM with optimal electron beam transfer.
Main Methods:
- Direct Simulation Monte Carlo (DSMC) method was employed to simulate gas density.
- Simulations covered the entire flow regime from free molecule to continuum flow.
- Electron beam transmission was calculated for argon, helium, neon, hydrogen, oxygen, nitrogen, and water vapor.
Main Results:
- Gas density profiles along the aperture axis were determined for argon.
- Electron beam transmission was quantified across a range of accelerating voltages (1-30 kV).
- The study analyzed transmission for multiple gases, including noble gases and water vapor.
Conclusions:
- The findings provide critical data for optimizing the design of pressure-limiting apertures in ESEM.
- Achieving optimal electron beam transfer is directly linked to aperture design and gas conditions.
- This research enables the development of higher-performance ESEM instruments.
Related Concept Videos
01:25Overview of Electron Microscopy
The wavelengths of visible light ultimately limit the maximum theoretical resolution of images created by light microscopes. Most light microscopes can only magnify 1000X, and a few can magnify up to 1500X. Electrons, like electromagnetic radiation, can behave like waves, but with wavelengths of 0.005 nm, they produce significantly greater resolution up to 0.05 nm as compared to 500 nm for visible light. An electron microscope (EM) can create a sharp image that is magnified up to 2,000,000X.
01:07Scanning Electron Microscopy
A scanning electron microscope (SEM) is used to study the surface features of a sample by using an electron beam that scans the sample surface in a two-dimensional manner. Typically, areas between ~1 centimeter to 5 micrometers in width can be imaged. SEM can be used to image bacteria, viruses, tissues as well as larger samples like insects. Conventional SEM gives a magnification ranging from 20X to 30,000X and spatial resolution of 50 to 100 nanometers.
Fundamental Principles
Accelerated...
Fundamental Principles
Accelerated...
01:15Transmission Electron Microscopy
In 1931, physicist Ernst Ruska—building on the idea that magnetic fields can direct an electron beam just as lenses can direct a beam of light in an optical microscope—developed the first prototype of the electron microscope. This development led to the development of the field of electron microscopy. In the transmission electron microscope (TEM), electrons are produced by a hot tungsten element and accelerated by a potential difference in an electron gun, which gives them up to 400 keV in...
01:20Preparation of Samples for Electron Microscopy
To be visualized by an electron microscope, either transmission or scanning, biological samples need to be fixed (stabilized) so the electron beam does not destroy them and dried thoroughly (desiccated/dehydrated) so the vacuum does not affect them. Fixation needs to be done as quickly as possible because the sample properties will start changing as soon as it is removed from its natural environment. For example, in a tissue sample, the oxygen levels begin decreasing, causing an altered...
01:22Overview of Microscopy Techniques
The early pioneers of microscopy opened a window into the invisible world of microorganisms. In 1830, Joseph Jackson Lister created an essentially modern light microscope. The 20th century saw the development of microscopes that leveraged nonvisible light, such as fluorescence microscopy that uses an ultraviolet light source and electron microscopy that uses short-wavelength electron beams. These advances significantly improved magnification, image resolution, and contrast. By comparison, the...